CA1167880A - Closed pressure actuated system for placement bucket - Google Patents

Abstract

CLOSED PRESSURE ACTUATED SYSTEM
FOR PLACEMENT BUCK
ABSTRACT
A placement bucket for placing material such as concrete in forms by manipulation of clam shell gates in response to action of a power cylinder makes use of a hydraulic fluid system which prevents opening the gates of a full or partially full bucket of material unless there is a sufficient reserve of pressure and fluid volume to make certain of closing the gates at any time. The system is provided with a precharged fluid supply under pressure into which additional fluid is diverted when generated in a master cylinder by lifting a piston against the weight of the bucket and its contents.
A sequence valve prevents flow of fluid to the power cylinder until an optimum amount of fluid pressure and volume is reached. An auxiliary direction valve in a fluid return line can be manipulated to temporarily block return flow of fluid from the exhaust side of the power cylinder to a reservoir, in that way to temporarily fix the partially of full open position of the gates.

Description

CLOS~D PRESSURE ACTUATED SYSTEM
FOR PLACEMENT ~UCKET
The present inventlon relates to a pressure actuated system, and partlcularly a closed pressure actua-ted system for a materlal placement bucket equtppedwlth a dlspenslng gate.
In plactng of wet concrete tn forms, and es-peclally for haavy constructlon work, a common exped bnt has been to make use of a bucket whlch can be loaded wlth concrete at ~ oonvenlent source, then Itfted~ and moved to a posltlon above the unfllJed form where the concrete ts released by manlpulatlon of a gate at the bottom of the bucket, Because gates are often large, as Is necessary when buekets contaln many cublc yards of seml-flu1d concrete It has boen found adv~nt~geous, and vlrtually neces~ary, ~o use a power actuated gate. ~oth llquld power and gas power qy~tems have been made use o~. Customarlly gas or ~quld p~essur~ ~rom an out~tde source ~s fed to the bueke~, thereby to p~ovlde the power for op~ratlon.
~0 A problem whtch has been encountered Is one where, a~tor the gata has been opened, at a locatlon remote from the source of power, Insufflc)ent~po~er remalns to completely ctosa the gate. When ~hts occurs before the bucket Is completeiy emptled, wet concreté then gets spllled at locatlons where lt Is Yary-unde~lra~l`e.
So~e exp~dlen~s have heretotor~ been devlsed for maklng cer~atn of ~here belng ample reserve power to close the ~ate at any tlm~. Reference Is made to Unlted States ; Patent Nos~ 4,161,135 and 3,104,125, More re~ently ~ystems have been deYlsed whlch dlspense wtth the need for upplylng a gas or llqutd power f~om an extern~l souree. Such systems make use o~ one or mo~e mast6r cy~lnder assembltes, the cyl1nder belng mounted on the bucket and a p~ston belng attached to the llttlng ; 35 cab b ~o that the welght of the bucket and tts contqnts act3ng agalnst the pls hn durtng the llftlng cycle generates adequatc power and Yolume for the operatlng fluld, be It gas or Itqutd, whlch Is subsequently used as the power for opening and closJng the bucket gates.

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-2-Slnce, In a system of the klnd last mentloned, there Is a ~Intte llmlt to the amount of power whlch can be generated and the volume of fluld whtch can be made avatlable for each plac0ment cycla, many of such systems frequently run out of power and also run out of fluld In suf~lclent qu~ntlty to be certaln o~ closlng the gates should some wet concrete remaln In the bucket. Expedtents for holdlng power In reserve, under clrcumstances where the power Is supplled from an outslds source, have not besn readtly adaptable to buckets where the power Is gener-ated by llftlng the bucket and Its contents.
As a make-shlft assuranca of haYlng adequate power, one practlce has been to add welght to the bucket over and above the welght of the bucket and Its contents so that adequate welght will rematn tn the system eYen after the bucket Is empty. An Important drawback to such an expedlent ts that undcr such clrcumstances the bucket ts alway~ overwelght> requlrlng more power to be moved abou~, a more rugged constructlon for the 11ftlng and transpor~a-tlon expedlents, such as cranes and trolley, and undue weardue to the excess welght. In actual practlce, bacause o~
the slze of equlpment of thls klnd, scrap iron In the form of rallroad càr whealsJ rails, and the llke, have been strapped to buckets, In that way to add to the welght.
2~ It Is tharefore the purpose of the present In-ventlon to provlde an Improved pressure actlvated system whlch wlll o~ercome the problems In system presentty belng used to operate materl~l placement buckets.
More speclflcally, ths present Inventlon pro-vldes a closed fluld pressure actuated system for a materlalplacement bucket equlpped wlth a dtspenslng gate, operatlng cyllnder means ~or sald gate havlng opentng and closlng sldes, and plston means In sald cyllnder means In operatlng engagemant wlth sald gate havlng full openlng and closlng 3S strokes, sald system comprlslng a charge of non-compresslble hydraullc fluld normally under pressurs~ llftfng means for the bucket, a pressure generatlng master cyllnder assembly havlng one oomplementary part attached to the bucket and another co~plementary part attached to the llfttng ~sans and adapted to generate addltlonal fluld pressure, a plurallty o~ traverse llnes between sald operatlng cyllnder means and sald master cyllnder assembly, fluld accumulator means In communlcatlon wlth sald traverse llnes for accumulatlon of a S quanttty of ~luld under pressure generated by the llftlng of sald bucket and storage of sald fluldt sald accumulator msans comprtslng a closed chamberJ a flrst portlon of sald closed chamber contaln1ng compresstble fluld under pressure, a sacond portlon of sald closed chamber contatnlng a quantlty of sald non-compresslbls fluld and dlaphragm means comprlstng a separator between satd compresslble flutd and satd non-compresslble ~luld, one of said traverse llnes belng In communlcatlon wlth the opsnlng slde of sald operatlng cyltnder means and another of sa1d traverse llnes belng In communlcatlon wlth the closlng slde of the opera-tlng cyllnder means, and a prlmary dlrectlonal control valve In communlcatlon wlth sald traverse llnes, sald prlmary dtrectlonal control valve havlng a normal posltlon Interconnecting sald master cyllnd~r assembly and sald accumulator means wlth the closlng slde o~ sald operatlng cylInder means and havlng an actuatlng posltlon Inter-connectlng satd master cyllnder assembly and sald accumula-tor means wlth the closlng stde of sald operatlng cyllnder means and havlng an actuatlng posltlon Interconnectlng sald master cyllnder asscmbly and sald accumulator means wlth the openlng slde of fhs operatlng cyJlndar means.
The tnventton conslsts of the constructlon, arrangement> and comblnatlon of the varlous parts of the devlca servlng as an example only of one or more em-bodlments of the tnventlon, whereby the obJects contem-plates are attalned, as herelnafter dlsclosed Tn the speclflcaflon and drawings, and polnted out In the appended clalms.
In the drawtngs:
FIGURE I Is a slde elevatlonal vtew of a typtcal large volume placement bucket featurlng hydraullc actuated clam shell gates.
flGURE 2 Is a schematlc exploded vtew of Infer-related m~chanlcal and hydraullc components.

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FIGURE 3 Is a partlal schematlc vlew of the hydraullc clrcult In gate closlng attltude.
FIGURE 4 Is a vlew slmllar to Flgure 3 but In gate open attltude.
In an embadtment of the Inventlon chosen for the purpose of ~llustratlon there Is shown a bottom openlng concrete placement bucket tndlcated generally by tha reference character 10 provlded wlth a palr of clam shell g3tes 11 and 12, a frame 13 enabllng 1t to be rested on a supportlng surface 14, and a sltng 15 provided wlth a llfttng hook 16 for attachmsnt of an appreprlate cable 16 ~FTgure 2).
The bucket features a hopper ~7 wlth slde walls 18 ~loplng progres%tvely Inwardly toward a chute 19 at the bottom, the lower end of whlch has an openlng 20 closed by the clam shell gates 11 and 12.
The gates 11 and 12 are of substantlally conven-tlonal constructlon, provlded wlth respectlve wlngs 21 and 22. The wlngs are plveted about tndlvldual plvot axes 23 and 24, Intermeshlng gear t0eth 25 and 26 belng made useof so that when the gate 12 Is moved elther toward open posltlon or ciosed posttlon, the gate 11 wllt move a correspondlng amount In the opposlte dlrectton. Fluld operatlng cyllnders ~8, 28 , one o~ whtch Ts shown In Flgure 1, provlde power and movement for respecttve piston rods 27, 27 whlch In turn are plvotally attached to a brackat 29 of the gate 12. A bracket 30 provldes for a plvotal attachment of the upper ends of the operattng cyltnders 28t 28 .
A base rtng 31~ whlch Is adapt~d to rest on the supporttng surface 14, provldes a support for columns 32, an upper rtng 33 belng attached to upper ends of the col-umns, where the hopper 17 Is attached.
Of specTal stgntflcance are tle master cyllnders 35 40 and 41. For the cyllnder 40 there Is a cyllndrlcal Jacket 42, at the lower end of whlch ts a cap 38 havlng a plvot pln 39 attachTng the cyl1ndrlcal Jacket ~o the base rlng 31.
Wlthln the cyllndrlcal Jacket 42, as better shown , ~.

ln Flgure 2, Is a chamber 43 accomodatlng a plston head 44 part1tlonlng the chamber tnto an upper sectlon 46 and a lower sectlon 47. A plston rod 45 Interconnects tha plston head 44 wtth the sllng 15. The master cyllnder 41 Is equlpped tn ths sa~e ~shlon as has been descrlbed for the master cyllnder 40.
Although the sllng 15 and Its llftlng hook 16 have for a prlmary functlon llftlng the bucket lO and transportlng It from a loadlng posttlon to a dump or con-crete placement posttion, the sllng has a second Importantfunctlon. When the bucket Is at rest on a supportlng sur-face 14, the ptston head 44 bottams agalnst a cushlon 48 at a lowar end 49 of the cyllnder Jacket 42. Although the welyht of the sllng, plston rods 45 and ptston heads 44 may be d0pended upon to move the plston heads to the Iower end¢ 49, sprlngs 50 may addltlonally be provtded.
Slnce the chamber 43 of the cyllnder Jacket 42 In each case ts part of the llquld hydr~ultc fluld operatlng system, when the plston heads are In thelr lowermost posltlon, the upper sectlons 46 wlll be at maxlmum capaclty for the fluld, whatever It may be. Thereafter, when the sllng 15 Is llfted, as by means of the llftlng hook 16, the plston heads wlll be flrst pulled upwardly wlthtn fhe respectlve chambers 43, thereby to generate llquld pressure ~5 in the upper sectlons 46 unttl the liquld pressure Is at a potnt comparaDle to the welght of the bucket and contents, whereafter contlnued upward llft of the llfting hook 16 wlll lt~t the bucket off the supporttng surface so that It can be transported to a deslred locatlon.
The fluld system, preferably hydraullc In the chosen form of the tnventton, whtch ts supplted by the Ilquid under pressure generated In the cyllndrlcal Jackets, supplles the hydraulic system, as shown In Flgures 2, 3 and 4, for openlng and closlng the clam shell gates 11 and 12. Once the system has been charged wlth an adequate amount of llquld hydraultc flutd~ there need be no further outstde supply of fluld nor sourceof pressure for operatton of the gates.
In the hydraultc flutd system, as deplcted tn Flgures 2 3 and 4 a llquld Itne 55 Intercommunlcatlng wlth the upper sectlons 46 of the respectlve master cyl-lnders 40 and 41 Is In communtcation wlth a fluld llne 56 through an upwardly open check valve 57 wlth respectlve accumulators 58 and 59. For added effectlveness the accumulators 58 59 may have the left-hand chambers 60 precharged w1th a compressTble fluld to a speclftc pressure supplled through llnes 61 through approprlate shut-off valves 62. In the accumulator 58 a movable dlaphragm 63 separates the left-hand chamber 60 from a r1ght-hand chamber 65. It Is of interest that the Itqutd tn these rlght-hand chambers 64 and 65 Ts always under soms pressure and that such pressure Is avallable to both openlng and closlng sldes of the operatlng cylInders 28~ 28'. By reasonof the presence of an Inltlal quantlty of the Itquld hydraullc fluld In the rlght-hand chambers 64 and 65 where tt serves to augment the quantlty and pressure of llqutd hydraullc fluld tn the master cyl~
tnders 40 and 41 there wlll always be a quantlty of the llquîd hydraullc fluld substantlally In excess of that needed to actlvate the operatlng cyllnders 28J 28 for each Inltlal actuatlon of -the operatlng cyllnders.
By reason of the dlstrlbutton of the llquld hydraullc fluld Just made reference to ths master cylln-ders 40 and 41 need not be llmlted to a capaclty no lessthan the capactty of the operatlng cylInders. In thls arrangement the accumulators are therefore always In constant communtcation wlth and a functlonal part of the system. They are accordlngly not safety features to be cut Into the system and called upon only In the event of an emergency.
A fluld llne 66 supplled by both of the accumulators 58 and 59 communtcates wlth a prlmary dl-rectlon control valve 67. From the prlmary dlrectlon control valve 67 one fluld traverse Itne 68 Is ln commu-nlcatlon wlth the openlng stde of respectlve operatlng cylinders 28 and 28 . A second fluld traverse tlne ~9 communlcates between the prlmary dlrectlon control valve 67 and the closlng slde of the operattng cylinder 28.

A re-turn llne 70 from the prlmary dtrectlon control valve 67, In whlch is located a sacondary dlrec-tlon control valve 71, communlcates through a return llne 72 wlth a reservolr 73. From the reservoir 73 a re-supply llne 74, In whlch Is a check valve 75, Interconnects wlth the fiutd llne 56 prevlously made reference to.
For a more detalled understand1ng of the opera-tlon of the hydraullc fluld system of thls embodlment of the Inventlon, refarence Is made to Flgures 3 and 4 where partlcularly fn Flgure 39 the dlrectlon control valves 67 and 71 are shown in thelr normal posltlons. Normal posl-tlon for the prlmary dlrectlon control valve Is closlng po-sltlon for the operatlng cyl1nder 28. As shown In Flgure

3, the prlmary dlrectton controi valve 67 Is open between the fluld llne 66 and the fluld traverse llne 69, and also open betw0en the fluld traverse llne 68 and the return Itne 70. The secondary dlrectlon control valve 71 Is also open to provtde ommunlcatlon be-~ween the return llne 70 and the return llne 7~ and thence to reservolr 73.
In operatlon let It be assumed that the handles of the dlrectlonal control vaives 67 and 71 are In the normal J upper posltlons shown In Flgure 3, the bucket rsstlng on the supporttng surface 14 at a loadlng statlon.
In thls attltude the gates 11 and 12 are forced to closed posltton.
Wlth the bucket 10 now belng fllled ~Ith Its load o~ wet concrete, the sllng 15 Is llfted by appllcatlon of the cable 16 to the llftlng hook9 and the plston heads 44 are pulied upwardly agalnst the volume ~f hydraullc fluld tn the upper sectlons 46J the upward motlon belng reslsted by ~he welght of the bucket and Its contents. As a con-sequence, pressure Is generated In the hydraullc fluld In the upper sectlons 46, and the hydraullc fluld flows through the fluld llnes 55 and 56. Not belng able to pass the check valve 75, but belng able to pass the check valve 57, the fluld charges the rlght-hand chambers 64 and 65 of the respectlve accumulators 58 and 59, shlftlng the dla-phragm 63J 631 agalnst the supercharge of the compresslble fluld In the left-hand chambers 60 and 60 . Thls condltlon prevalls as long as llf-ilng pressure Is applled to the slIng 15 as it Is moved from a loading statton to a dls-charge statlon over forms whlch are to be fllled.
Upon reachlng the dtscharge statlon over the form, the gates are designed to be opened io the extent : deslred by the operator. To open -i-he gates~ the operator pulls downwardly upon a chaln 80 of the primary dlrectlon-at control valve 67. Thls moves the valve handle down - agalnst pressure of the return sprlng 81 until -the valve handle Is in lowermost positlon. ~Ith the valve handle In Its lowç~most posltlon, flutd under pr0ssure from the ~luld Itne 65 Is dlverted to the fluld -iraverse llne 6i3 whlch supplles the openlng slde of both of the operatlng cyllnders 28, 2~'. At the same tlme, the fluld traverse llne 69 In communlcatlon wli^h the closlng slde of the op-eratlng cyllnder ~8 Is dlverted -to the return llne 70.
Wlth the handle of ihe secondary dlrectlonal control valve 71 remalntng in Its normal upper posltlon~
the fluld from the opera-ilng cylInder 28 contlnues ~in Its path through the re-iurn llne 72 to the reservolr 73.
Should the operator wlsh to close -ihe gates at any ttme, It Is necessary only to release ihe chaln 80, where-~ upon by actlon of the return sprlng 81 the prlmary direc-j tlonal control valve handle will be moved upwardly to ths upper posltlon, cutting off flow to the opening ends of the operatlng cyllnders and dlrecting flow to the closlng end of the operating cyilnder 28.
Should the operator, for example, wlsh to freeze the gates at some selected partlally open posltlon, the chaln 80 Is f7rst pulled downwardly so as to shlft the handle of prlmary dTrectlonal control valve 67 to Its lower posTtlon9 as previously described, until the clam sheil gates are open to the extent deslred, at which polnt the operator pulls downwardly upon a chatn 82 of the secondary directlonal control valve ?1. Both dtrectlonal control valves wlll -ihen be in the positions shown in Flgure 4. The effect of this is that when the handle of the secondary directlonal controt valve 71 Is moved to Tts lower posltion as shown~ flow through the return Itne 70 to the returrl llne 72 15 blocked.
Slnce no more hydraullc fluld can flow out of the closlng end of the operatlng cylInder 28J hydraullc flutd trapped thereln prevents movement of the operatlng cylIn-ders 28, 28 any further toward openlng posltlon, andthe open posltlon prevlously achleved remalns fro~en or flxed.
Wlth the operator contlnulng to pull downwardly on the chaln 80 holdlng the handle of the prlmary direc-ttonal control valve tn Its lower posltlon9 If the chaln82 of the secondary dlrectlonal control valve 71 Is re-leased, flow wtll be resumed through the return llnes 70 and 72 from the closlng slde o~ the operatlng cyllnder 28 and the operatlng cyltnders wlll then contlnue to move In an openlng dlrectlon, supplted with fluld under pressure from the accumulators and the fluld llne ~6.
In the alternatlve, and assumtng both dlrec-tTonal control valves In the posltions of Flgure 4, If the operator should ralease pull on the chaln B0, the handle of the prlmary dlrectlonal control valve 78 wtll then be moved upwardly to Its normal posltton by actlon of the return sprlng 81. Whtle the handle of the secondary dtrect~onal control valve 71 remalns In Its lower posltlon because of ~enslon on the sprlng 82, no closlng of the gates wlll take place because hydraullc ; flutd ts trapped In the opposlte or closlng ends of the operatlng cyltnders 28, 28 because flow In the return lines 70, 72 to the reservolr Is blocked. Under thts clrcumstance, however, whan tenslon Ts released on the chaln 82 permlttlng the return sprlng 83 to move the handle of the secondary dlrecttonal control valve 71 to Its upper posltlon, the unblocked posltlon Is relteved, fluld can then flow from the lower ends of the operat1ng cyllndars Z8, 28 , and closlng wlll commence by actton of the operatlng cyltnder 289 supplled as It Is wlth fluTd under pressure on the closlng slde.
0~ spectal slgnlftcance ts the presence of a tpr~ssure actuated sequence valve 85 located In traverse line 6~, às~sho`wn t~n Flgur~ 2. The sequence valve 85 ~

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located In traverse llne 68, as 5hown In Flgure 2. The sequence valve 85 Is one of the conventlonal constructlon deslgned to rematn closed untll a selected pressure has been rsached fn the traverse line 68. Thls actton prevents flow through the traverse llne 68 to the openlng stdes of the operatlng cyllnders 28, 28 untll there has been a bulId-up of pressure In the accumulators 58 and 59, to-gether wlth approprlate volume, In excess o~ that needed to ultlmately close the clam shell gates ll and 12 once they have been opened.
Further stlll, tn the course of operatton, should the sequence valve 85 at any tlme sense when the pressure has fallen to a predetermlned level, It wlll block any further flow to the openlng slde of the operat-IS 7ng cyllnders and, as a conse4uence, there wlll rematnsufflclent pressure and volume to close the clam shell gates from whatever posltlon they may have been op~ned to.
As a further assurance agalnst malfunctlonl there may be provlded In the fluld traverse llne 68 a flow con~rol valve 86. A sultable adJustment of the flow control valve 86 may be made to determlne the speed af closlng for the clam shell gates or other speclal condl-tlon whlch may exlst. A slmllar type of flow control valve 87 may be pro~lded In the fluld traverse llne 69, llmltlng1he fiow of hydraullc fluid from the closlng slde of the operatlng cyllnder 28, to adJust the openln3 speed In order to sult prevalltng Job condttlons.
Cushlons 48 have been Identifled as provldlng a cushlonlng effect when the ptston heads 44 bottom In the cyifndrlcal Jackets 52. Presence of the accumulators 58, 59 supercharged Inltlally provtde a cushionlng effect when the bucket Is Inltlally holsted, thereby reductng hydraullc shock tn the system and aiso when the ptston heads bottom at the upper ends of the same cyllndrlcal Jackets. Addttlonal cushtons at the upper ends (not shown) may be provtded as needed.
To add further to the dependablllty of the system as a hydraullcally operated system, suctton stratners 88 and 89 may be located below the Itquld level 3~

90 In the reservolr 73 to malntain a clear flow through the re-supply Itne 74. A return llne fllter 91 ts suppiled for the return llne 72. A breather'flller unlt 92 may turther be provlded for the reservolr 73, a comparable-breather 93 belng supplled at the exhaust end of the opeFatlng cylrnder 28~. Breathers 94 ~ay also be provlded for lower ends 47 of the master cyllnders 40 and 41.
After the dumplng or placement cycle for con-tO crete from ~he bucket has been completed, the bucket Is returned to the loadlng statton and again permltted to rest upon the supporting surface t4. As tenslon Is re-leased on the llftlng hook 16, the plston heads 44 agaln move to thetr lowermost posltions In the cyllndrlcal Jackets of the master cyllnders 40, 41. Flutd flows from the reservolr 73 Into the upper sectlons 46. Accordingly,' once the bucket has been refllled wlth concrete the system Is Im~edlately ready ~or another placement cycle of operatlon.
It should be noted that for a partlcular bucket deslgn or type of concrete belng.handled both the volume and the pressure generated by the master cyllnders 15 varled by selectlng cyllnders of dlfferent bores and strokes. The volume dlsplacsd by the master cyllnders ~5 must be approprlate to ylold the deslred number of gate cycles. Llkewlse, the bore of the master cyllnders must be approprlate to yield the deslred pressure to open and close the gate under the vartous loadlng condltlons assumed by the bucket under actual field clrcumstances.
Whlle a partlcular embodlment of the present invention has been shown and descrlbed, It will be obvlous to those skllled In the art that changes and modlflcatlons may be made wlthout departlng from the lnventlon In Its broader aspects, and therefore, the alms of Its appended clalms Is to cover all:changes and modlfIcations as falJ
wlthln the scope of the appended clalms.

Claims (12)

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1. A closed fluid pressure actuated system for a material placement bucket equipped with a dis-pensing gate, operating cylinder means for said gate having opening and closing sides, and piston means in said cylinder means in operating engagement with said gate having full opening and closing strokes, said system comprising a charge of non-compressible hydraulic fluid normally under pressure, lifting means for the bucket, a pressure genera-ting master cylinder assembly having one complementary part attached to the bucket and another complementary part attached to the lifting means and adapted to generate additional fluid pressure, a plurality of traverse lines between said operating cylinder means and said master cylinder assembly, fluid accumulator means in communica-tion with said traverse lines for accumulation of a guanti-ty of fluid under pressure generated by the lifting of said bucket and storage of said fluid, said accumulator means comprising a closed chamber, a first portion of said closed chamber containing compressible fluid under pressure, a second portion of said closed chamber con-taining a quantity of said non-compressible fluid and di-aphragm means comprising a separator between said com-pressible fluid and said non-compressible fluid, one of said traverse lines being in communication with the opening side of said operating cylinder means and another of said traverse lines being in communication with the closing side of the operating cylinder means, and a primary directional control valve in communication with said traverse lines, said primary directional control valve having a normal position interconnecting said master cylinder assembly and said accumulator means with the closing side of said operating cylinder means and having an actuating position interconnecting said master cylinder assembly and said accumulator means with the opening side of the operating cylinder means.

2. A fluid pressure actuated system as in Claim 1 wherein said accumulator means has a precharged pressure in an amount of substantially one-third of the maximum pressure generated by the master cylinder assembly.

3. A fluid pressure actuated system as in Claim 2 wherein the precharged pressure of the accumulator means is the pressure of a compressible fluid in a sep-arate sealed expandable chamber in said accumulator means.

4. A fluid pressure actuated system as in Claim 1 wherein the pressure generated in said master cylinder assembly is in excess of optimum operating pressure for said operating cylinder means and there is a pressure actuated sequence valve in a selected one of said traverse lines for the opening of the sequence valve and initiation of an opening cycle for the operating cylinder means until the volume and pressure of fluid in the accumulator means is at least equal to that re-quired for a complete closing cycle.

5. A fluid pressure actuated system as in Claim 1 wherein there is a flow control valve in the traverse line for the opening side of the operating cyl-inder means whereby to control the speed of opening the gate.

6. A fluid pressure actuated system as in Claim t wherein there is a flow control valve in the traverse line for the closing side of the operating cylinder means whereby to control the speed of closing of the gate.

7. A fluid pressure actuated system as in Claim 1 wherein there is a flow control valve in the traverse line for the opening side of the operating cylinder means whereby to control the speed of closing of the gate.

8. A fluid pressure actuated system as in Claim 1 wherein there is a flow control valve in selected ones of said traverse lines for the operating cylinder means whereby to control the speed of gate movement for both the opening and closing cycles.

9. A fluid pressure actuated system as in Claim 1 wherein there is a second directional control valve in another selected one of said traverse lines downstream from the primary directional control valve, the second directional control valve having a normal position passing fluid from the primary directional con-trol valve toward the master cylinder assembly and a second position blocking passage of fluid from said primary directional control valve.

10. A fluid pressure actuated system as in Claim 9 wherein there is a fluid reservoir between said second direction control valve and said master cylinder assembly.

11. A fluid pressure actuated system as in Claim 9 wherein there is automatic means in operative relationship with the second directional control valve acting in a direction to move said second directional control valve to said normal position.

12. A fluid pressure actuated system as in Claim 1 wherein the quantity of hydraulic fluid accumu-lated by said accumulator means is not less than the quantity of hydraulic fluid needed for said full strokes of the piston means.